Characterization of supported solid thin films of Laponite clay. Intercalation of rhodamine 6G laser dye.

The morphology of thin films of Laponite (Lap) clay elaborated by the evaporation method and spin-coating technique was analyzed by atomic force microscopy and scanning electron microscopy, indicating a better quality film for the latter procedure. Rhodamine 6G (R6G) laser dye was intercalated into these films by ion exchange mechanism, performed by immersing the clay film into adequate dye solutions in which the effect of the dye concentration, immersion time, and nature of the solvent on the adsorption process were checked. The adsorption of R6G at the interlayer space of Lap was analyzed by the X-ray diffraction technique, and the presence of several R6G species (monomers and aggregates) was characterized by absorption and fluorescence spectroscopies. Less viscous solvents lead to higher dye loadings, suggesting a diffusional process for the intercalation of the dye in the interlayer spaces of Lap, and polar solvents favor the swellability of the interlayer space giving rise to a more homogeneous distribution of R6G molecules through the film and decreasing the dye aggregation. With the aging of the samples, the dye molecules can migrate through the interlayer spaces, leading to a more expanded distribution of R6G molecules and to the dye deaggregation.